Commercial food processing facilities and the food products moving through such facilities must be maintained in a scrupulously clean condition. One method of achieving this high level of cleanliness is by means of high-pressure, hose-down cleaning with steam, hot water and/or chemical solutions. During the course of the cleaning operation, electric motors utilized in the manufacturing process are exposed to harsh, oxidative conditions. These “washdown motors” as they are referred to in the trade are also used in chemical manufacturing facilities and the like.
In the course of the cleaning process, the level of humidity in the facility being cleaned increases and corrosive chemicals can become dissolved in the wastewater. Steps can be taken to limit direct contact between the wastewater and the motor itself by locating the motor on a pedestal or other raised area. Nonetheless, the resultant high humidity, particularly in combination with dissolved chemicals in the atmosphere, produces a highly corrosive environment. While precautions can be taken to lessen the ingress of moisture into the motor interior by employing multiple seals and water-tight fittings, some amount of corrosive solution will inevitably enter into the motor interior—around the shaft or through inlets for electrical wiring, resulting in chemical attack on the winding or bearings.
One other factor that complicates the design of a corrosion-proof motor is heat. Although copper is a very good conductor of electricity, it is subject to I2R losses in the form of heat. In order for an electric motor to operate effectively, this heat build-up must be dissipated, typically through the motor's outer shell or casing.
This combination of steam, heat, moisture and other corrosive factors typically results in very short life cycles for washdown motors. It is not uncommon for such motors to fail within a matter of a few months; in some applications failure occurs in a matter of days or weeks. Motor failure is generally due to chemical attack on the copper winding or bearings of the electric motor—in particular, the fixed (or stator) motor windings. This need to constantly replace washdown motors is an added expense to food processors and other users of such motors. Additionally, the need to suspend operations while repairs are made is disruptive to the flow of product through the processing facility and results in increased labor costs.
Thus, there is the need for an electric motor which can be used in washdown applications and which exhibits increased resistance to oxidative attack.